作者: Guangyong Xu , J. F. DiTusa , T. Ito , K. Oka , H. Takagi
DOI: 10.1103/PHYSREVB.54.R6827
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摘要: We report an inelastic-neutron-scattering experiment on single crystals of the one-dimensional spin-one antiferromagnet ${\mathrm{Y}}_{2}$BaNi${\mathrm{O}}_{5}$. The data show that this compound is a nearly ideal material for studying Haldane conjecture in Heisenberg limit. In particular, gap at $\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{q}=\ensuremath{\pi}$ almost isotropic, taking values 7.5(1), 8.6(1), and 9.6(1) meV polarizations parallel to three principal orthorhombic axes respectively. Interchain coupling along edges unit cell found be very weak ($\frac{{J}^{\ensuremath{'}}}{J}l~5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$). Finally, we defects our sample 1% level cause visible broadening excitation \~{}\fi{}}{q}=\ensuremath{\pi}$.